What is the difference between High Complexity and Low Complexity AAC files? I encoded an album at 192kbps using iTunes and noticed they are tagged as Low Complexity files. Does this refer to the complexity of the music or the type of encoding used? Please explain the difference to a poor fool such as I.


Conrad

There is no such thing as high complexity. More information on different profiles: http://www.audiocoding.com/wiki/index.php?page=AAC

Answers that question. Thanks.

HC-AAC doesn't exist. You're probably talking about HE-AAC (High Efficiency AAC). HE-AAC is ment mostly for low-bitrate encodings (up to 96kbps). Everything above that should be encoded with LC-AAC.

HE-AAC is AAC + SBR technology, the same technology used in MP3Pro (which also is a low-bitrate encoder).

What about Main and LTP ? Why aren't they never employed? Is there any noticeable increase in quality?

LTP is for low bitrates.

If I remember correctly, the main profile requires significantly more resources to encode and decode and the quality gain isn't as big as the HE profile has using sbr.

But HE is for low bitrates only. What exactly main profile offers that LC does not? And how significant is the change in resource usage?

http://www.audiocoding.com/wiki/index.php?page=AAC

Menno

IIRC, the main profile takes something like 40% cpu usage, while lc only needs about 10% or so. in any case, I might very well be wrong with the numbers, but I'm quite positive that the difference was significant.

edit: ah, Menno was first... and more acurate

edit: doubleposted. admins: please feel free to delete this post.